feat: self-update of master and agents (#15)

internal/agent/updater/compose.go

@@ -11,8 +11,6 @@ import (
 
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/api/types/filters"
-
-	"github.com/shcizo/package-updater/internal/protocol"
 )
 
 const (
@@ -71,6 +69,7 @@ func dockerEnv() []string {
 // ComposeDocker is the subset of the Docker SDK ComposeExecutor needs.
 type ComposeDocker interface {
 	SelfInspector
+	HelperDocker
 	ContainerList(ctx context.Context, opts container.ListOptions) ([]container.Summary, error)
 }
 
@@ -95,7 +94,14 @@ func NewComposeExecutor(cli ComposeDocker, resolve *Resolver, selfID string, run
 // is), writes it to the stack's override file and recreates the service.
 // Working directory and config files come from the service's container
 // labels on this machine, never from the job. It returns the pinned ref.
-func (e *ComposeExecutor) Execute(ctx context.Context, job protocol.JobStart, out io.Writer) (string, error) {
+//
+// When the service is the agent's own container, the recreate runs in a
+// helper container instead (see selfUpdate), because it stops this process.
+func (e *ComposeExecutor) Execute(ctx context.Context, job Job, out io.Writer) (string, error) {
+	// What the job has printed so far goes into the helper's labels.
+	soFar := &tailBuffer{max: selfUpdateOutputMax}
+	out = io.MultiWriter(out, tailWriter{soFar})
+
 	project, service := job.ComposeProject, job.ComposeService
 	cts, err := e.cli.ContainerList(ctx, container.ListOptions{
 		All: true,
@@ -114,10 +120,11 @@ func (e *ComposeExecutor) Execute(ctx context.Context, job protocol.JobStart, ou
 	configFiles := cts[0].Labels[labelConfigFiles]
 	envFileLabel := cts[0].Labels[labelEnvFile]
 
-	roots, err := MountRoots(ctx, e.cli, e.selfID)
+	self, err := inspectSelf(ctx, e.cli, e.selfID)
 	if err != nil {
 		return "", err
 	}
+	roots := rootsOf(self)
 	files, dir, err := composeFiles(roots, configFiles)
 	if err != nil {
 		return "", err
@@ -163,8 +170,17 @@ func (e *ComposeExecutor) Execute(ctx context.Context, job protocol.JobStart, ou
 	}
 
 	base := composeBase(project, workingDir, files, envs)
+	isSelf := false
+	if self.ContainerJSONBase != nil && self.ID != "" {
+		for _, ct := range cts {
+			isSelf = isSelf || ct.ID == self.ID
+		}
+	}
 	for _, step := range [][]string{{"pull", service}, {"up", "-d", service}} {
 		args := append(append([]string(nil), base...), step...)
+		if isSelf && step[0] == "up" {
+			return e.selfUpdate(ctx, job, self, workingDir, args, pinned, out, soFar)
+		}
 		fmt.Fprintf(out, "$ docker %s\n", strings.Join(args, " "))
 		tail := &tailBuffer{max: errorOutputTail}
 		if err := e.run(ctx, workingDir, io.MultiWriter(out, tailWriter{tail}), args...); err != nil {